The present invention relates to the field of practice ammunition and, specifically, to an ammunition projectile that can mark its point of impact both by day and by night.
More particularly, the invention concerns a device, incorporated into a projectile, that provides for marking the point of impact of the projectile when the projectile strikes a target. As used herein, the term “projectile” is intended to include both mortar ammunition and artillery ammunition.
Impact marking projectiles are well known in the art. Marking projectiles which use a dry powder, such as a red powder dye, for marking the impact by day are known, for example, from the U.S. Patent Publication No. 2006/0032393 to Haeselich. Marking projectiles which use chemi-luminescent materials for marking their impact by night are also known. Reference is made, for example, to the U.S. Pat. No. 6,619,211 and the aforementioned Patent Publication, both to Haeselich, which disclose such practice ammunition. U.S. Pat. Nos. 6,497,181 and 6,990,905 to Manole et al. also disclose similar devices.
The aforementioned U.S. Pat. No. 6,619,211 was reissued as U.S. Pat. No. RE 40,482. This reissue patent discloses and claims an ammunition projectile containing two chemi-luminescent components which are mixed on set-back; that is, upon the initial acceleration of the projectile. The components, which are liquid, are contained in separate frangible compartments within the projectile that are designed to be broken by the acceleration and/or centrifugal forces when the projectile is fired from a weapon. When mixed, the liquid components react and produce a luminescent glow. When the projectile impacts a target the mixed chemi-luminescent material is released and dispersed to mark the point of impact. The projectile has a translucent ogive so that it can also emit light during flight.
The Haeselich reissue patent, referred to above, discloses two compartments, arranged either side by side or one above the other in the projectile, with a frangible partition between them. While this arrangement is satisfactory under most conditions, it is not fully reliable in that the frangible partition can sometimes withstand the acceleration and centrifugal forces experienced during launch, so that it does not break and allow mixing of the components.